ABO Exam Practice Test - Practice Exam & Study Guide for the American Board of Opticianry

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Where is prism verified in Progressive Addition Lenses (PALS)?

a. At the dot beneath the fitting cross

Prism verification in Progressive Addition Lenses (PALS) is typically done at the dot beneath the fitting cross. This is because the fitting cross represents the reference point for fitting the lenses on the patient's face, and the dot beneath it is used to mark the optical center of the lenses. The other options are incorrect because

- B: "Down" is a vague term and doesn't specify a specific location for prism verification.

- C: The apex of the cornea is not relevant for prism verification, as it is used for fitting regular single vision lenses.

- D: The vertex compensation formula is used to calculate prism power, but it is not the location where prism is verified.

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b. Down

c. Apex of the cornea

d. Vertex compensation formula